TW202235997A - Litho-aware source sampling and resampling - Google Patents

Abstract

A method includes determining a first transmission cross coefficient (TCC) operator of an optical system of a lithographic system based on an illumination source. The method includes sampling the illumination source by a first number of sampling points to produce a first discrete source and determining a second TCC operator based on the first discrete source. The method also includes determining an error between the first TCC operator and the second TCC operator. The method includes recursively adjusting the first number of sampling points to re-sample the illumination source and to re-determine the second TCC operator until the error is below a threshold level and a final discrete source and a final second TCC operator is determined.

Description

Lithography-aware source sampling and resampling

Embodiments of the present invention relate to sampling and resampling of lithography sensing sources.

Photolithography transfers the layout pattern of the mask to the wafer, while etching, implanting or other steps are applied only to the intended areas of the wafer. Transferring the layout pattern of the photomask to the photoresist layer on the wafer can lead to photoresist pattern defects, which is a major challenge in semiconductor manufacturing. An optical proximity correction (OPC) operation may be applied to the layout pattern of the reticle to reduce resist pattern defects. OPC can modify the layout pattern of the mask before the lithography process to compensate for the influence of the lithography process. In addition, an inverse lithographic transformation (ILT) can be performed on the layout pattern of the mask to further compensate for the influence of the lithographic process. An efficient OPC or ILT operation is required on the layout pattern of the reticle.

According to an embodiment of the present invention, a method for designing a layout includes: determining a first transmission cross coefficient (TCC) operation of an optical system of a lithography system according to an illumination source of the optical system of the lithography system The illumination source of the optical system is sampled by a first number of sampling points to generate a first discrete source; a second TCC operation of the optical system of the lithography system is determined according to the first discrete source determine an error between the first TCC operator and the second TCC operator; recursively adjust the first number of sampling points to resample the illumination source and re-determine the illumination source based on the resampled illumination source second TCC operator until the error is below a threshold level and a final discrete source and a final second TCC operator are determined; and performing an optical proximity correction (OPC) operation of a first layout pattern of a reticle , wherein the OPC operation uses the final discrete source and the final second TCC operator to determine a projected image of the first layout pattern of the reticle on a wafer.

According to an embodiment of the present invention, a method for designing a layout includes: determining the lithography system according to an illumination source of an optical system of a lithography system and an exit pupil of the optical system of the lithography system a first transmission cross coefficient (TCC) operator of the optical system; sampling the illumination source of the optical system by a first number of sampling points at a first number of sampling positions to form a first discrete source; Determine a second TCC operator of the optical system of the lithography system according to the first discrete source and the exit pupil of the optical system; determine a distance between the first TCC operator and the second TCC operator error; recursively adjust the first number of sampling points and the first number of sampling positions to resample the illumination source and re-determine the second TCC operator based on the resampled illumination source until the error is within a threshold error within range and a final discrete source and a final second TCC operator are determined, wherein the threshold error range has an upper bound and a lower bound; performing an inverse lithography transformation (ILT) on a first layout pattern of a reticle operation, wherein the ILT operation uses the final discrete source and the final second TCC operator to determine a projected image of the first layout pattern of the reticle on a wafer for determining a of the first layout pattern ILT enhancement; and generating the ILT enhanced first layout pattern on a reticle substrate to fabricate a reticle.

According to an embodiment of the present invention, a lithography system includes: a main controller; a reticle; a reticle intensifier coupled to the main controller; an optical system including an illumination source and coupled to the main controller; a reticle projector coupled to the main controller and the reticle intensifier and configured to produce a projection on the reticle on a wafer; an analyzer module coupled to to the main controller, wherein the analyzer module is configured to receive the reticle to be produced on the wafer to produce a first layout pattern; the reticle booster is coupled to the analyzer module through the main controller , and configured to receive the first layout pattern from the analyzer module and perform one of an optical proximity correction (OPC) operation or an inverse lithography transformation (ILT) operation of the first layout pattern; the The reticle booster is further configured to determine a final discrete source and a final second TCC operator by: receiving a first number of sampling points from the analyzer module; the illumination source and the an exit pupil of the optical system to determine a first transmission cross coefficient (TCC) operator of the optical system of the lithography system; the illumination source of the optical system is sampled by the first number of sampling points to produce a first discrete source; determining a second TCC operator of the optical system of the lithography system according to the first discrete source and the exit pupil of the optical system; determining the first TCC operator and the second TCC An error between operators; recursively adjusting the first number of sample points to resample the illumination source and re-determining the second TCC operator based on the resampled illumination source until the error is below a threshold level and determining a final discrete source and a final second TCC operator; and wherein the reticle projector is configured to execute the reticle onto the wafer using the final discrete source and the final second TCC operator Projecting, for the OPC operation or the ILT operation, to determine a projected image of the first layout pattern of the reticle on the wafer.

The following disclosure provides many different embodiments or examples for implementing different features of the provided subject matter. Specific examples of components and configurations are described below to simplify the present disclosure. Of course, these are examples only and are not meant to be limiting. For example, in the following description, forming a first member over or on a second member may include embodiments in which the first member and the second member are formed in direct contact, and may also include embodiments in which the first member and the second member are formed in direct contact. An embodiment in which an additional component is formed between the second component so that the first component and the second component may not be in direct contact. Additionally, the present disclosure may repeat reference element symbols and/or letters in various instances. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or configurations discussed.

In addition, for ease of description, spatially relative terms such as "below", "below", "under", "above", "upper" and the like may be used herein to describe the relationship between an element or component and another(s) The relationship of elements or components, as drawn in the figure. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. Additionally, the term "consisting of" can mean "comprising" or "consisting of". In this disclosure, the term "one of A, B and C" means "A, B and/or C" (A, B, C, A and B, A and C, B and C or A, B and C) , does not denote one element from A, one element from B, and one element from C unless otherwise stated.

In some embodiments, one or both of OPC operations or ILT operations are applied to the layout pattern of the reticle to reduce photoresist pattern defects. In some embodiments, both OPC and ILT operations are performed iteratively. OPC and ILT modify the layout pattern of the photomask, and project the modified layout pattern of the photomask into the pattern on the photoresist material layer on the wafer through the optical system of the lithography system. The projected pattern on the photoresist is compared to the target layout pattern, and an error between the projected pattern on the photoresist and the target layout pattern is calculated. Depending on the calculated errors and/or the presence of certain defects (eg, bridging or narrowing), the layout pattern of the reticle is further modified by OPC and/or ILT operations. The iterative method is repeatedly applied until the defect is corrected and/or the calculated error is below a threshold level. In some embodiments, the projection of the layout pattern of the reticle onto the photoresist layer of the wafer is performed by simulating the projection, and the projected pattern on the photoresist layer of the wafer is calculated. In analog projection, an illumination source, such as a light source or a laser source, of the optical system of the lithography system is sampled through a sampling grid. The resolution of the sampling grid directly affects the complexity and accuracy of the simulated projection. Simulated projections can be fast if lighting source sampling is performed at low resolutions, but simulated projections can lose accuracy. Conversely, if lighting source sampling is performed at high resolution, simulated projection may be slower and time-consuming, but simulated projection may be more accurate. Therefore, the resolution at which the illumination source is sampled defines the speed and accuracy of OPC and ILT operations. Therefore, it is desirable to find a suitable resolution for sampling the illumination source.

FIG. 1 depicts a schematic diagram of an example integrated circuit (IC) manufacturing flow 100 . The IC manufacturing process 100 begins with the IC design module 102 providing a layout pattern M, such as a target layout pattern, to be produced as photoresist patterns for IC products on a wafer. The IC design module 102 is used in different steps of processing the IC product according to the specifications of the IC product to generate various layout shapes, such as geometric patterns. In some embodiments, the layout pattern M is represented by one or more data files with information about geometric patterns. In some embodiments, optically projecting the layout pattern of the reticle onto the wafer during the lithography process degrades the layout pattern of the reticle and creates pattern defects on the photoresist layer of the wafer. Optical proximity correction (OPC) operations can be applied to the layout pattern of the reticle to reduce pattern defects on the wafer. OPC can modify the layout pattern of the mask before the lithography process to compensate for the influence of the lithography and/or etching process. IC fabrication flow 100 also shows reticle booster 104 . As will be described in more detail below with respect to FIG. 2A , in some embodiments, reticle booster 104 performs OPC. The reticle enhancer 104 produces an OPC-processed (eg, corrected or enhanced) layout pattern M' on the reticle. In some embodiments, the enhanced layout pattern M' is represented by one or more data files with enhanced geometric pattern information.

The IC manufacturing flow 100 further illustrates a reticle projection system 106 . In some embodiments, the reticle projection system 106 generates the enhanced layout pattern M' on the reticle. In some embodiments, reticle projection system 106 performs two functions. As a first function, the reticle projection system 106 uses the data file of the enhanced layout pattern M' and uses an electron beam to generate the enhanced layout pattern M' on a reticle substrate (not shown here) to produce a pattern for the ICs. mask. Additionally, as a second function, the reticle projection system 106 optically projects the enhanced layout pattern M′ of the reticle onto the wafer 108 to generate the IC layout on the wafer 108 .

2A and 2B depict schematic diagrams of example reticle intensifiers and OPC enhanced layout patterns associated with target layout patterns. FIG. 2A depicts a schematic diagram of reticle intensifier 104 that receives target layout pattern M at the input of OPC intensifier 122 and generates enhanced layout pattern M′ at the output of step 150 . The reticle enhancer 104 performs an iterative process. In some embodiments, the reticle booster 104 includes an OPC booster 122 that receives the target layout pattern M to be generated on the wafer 108 from the IC design module 102 . The OPC enhancer 122 performs enhancement on the target layout pattern M, and generates an OPC-processed (eg, corrected or enhanced) layout pattern M′. As mentioned above, OPC is a lithography technique for correcting or enhancing the layout pattern M and adding an improved imaging effect to the target layout pattern M, so that the OPC-processed layout pattern M′ reproduces the target layout pattern M on the wafer 108 . For example, OPC is used to compensate for image distortion caused by optical diffraction. In some embodiments, the target layout pattern M is a data file having information of a geometric pattern to be produced on the wafer 108, and the OPC enhancer 122 modifies the data file and produces a corrected pattern representing the enhanced layout pattern M′ data file. In some embodiments, the target layout pattern M and the enhanced layout pattern M' are represented by vertices of the layout patterns in the data file. Thus, in some embodiments, the rounded corners and bends are represented by a curvilinear shape having a plurality of vertices and a plurality of line segments connecting the vertices, and the curvilinear shape is represented by a plurality of vertices in the data file.

FIG. 2A further illustrates a reticle projector 130 , such as a simulator for reticle projection, which is applied onto the enhanced layout pattern M' to produce the projected photoresist pattern 101 on the wafer. In some embodiments, the enhanced layout pattern M′ is a data file, and the reticle projector 130 simulates the projection of the enhanced layout pattern M′ on the wafer and generates the simulated projected photoresist pattern 101 . The projected photoresist pattern 101 is checked by the OPC verifier 140 for errors. In some embodiments, the OPC verifier 140 receives the target layout pattern M in addition to the projected photoresist pattern 101, and compares the projected photoresist pattern 101 with the target layout pattern M to find the target layout pattern M and the projected photoresist pattern M. The error between the projected photoresist patterns 101 . In some embodiments, when the error between the target layout pattern M and the projected photoresist pattern 101 is below a threshold level and there are no defects in the projected photoresist pattern (eg, bridges or narrowings as shown in FIG. 3 ). , the OPC verifier 140 verifies the enhanced, eg, OPC-processed, layout pattern M′. In some embodiments, after verifying the enhanced layout pattern M′, the OPC verifier 140 generates and sends a verification signal 103 . In some embodiments, OPC validator 140 stores enhanced layout pattern M' in a database. In some embodiments, instead of simulation results, a photoresist pattern is formed by using a photomask manufactured by enhancing the layout pattern M′, and the shape and size of the photoresist pattern are measured and fed back to the OPC booster. Regarding the reticle projector 130, FIGS. 7A and 7B are described in more detail.

The verification signal 103 is tested in step 150 and if the verification signal 103 is unsuccessful, eg, an error above a threshold level or a defect in the projected photoresist pattern 101 , further OPC enhancements are applied by the OPC enhancer 122 to continue the iteration. The iterations continue until the verification signal 103 is successful. When the verification signal 103 is successful, the enhanced layout pattern M′ is provided as an output of the reticle enhancer 104 . In some embodiments, the error between the target layout pattern M and the projected photoresist pattern 101 is defined as the distance between the boundary of the target layout pattern M and the boundary of the projected photoresist pattern 101 .

As shown, FIG. 2A includes a reticle generator 141 and an optical system 145 in addition to the reticle intensifier 104 . In some embodiments, the enhanced layout pattern M′ is sent to the mask generator 141 as a data file. The photomask generator 141 generates the enhanced layout pattern M′ on the photomask substrate to generate the photomask 143 . In some embodiments, the optical system 145 of the photolithography system uses the mask 143 to create a photoresist pattern on the photoresist layer of the wafer 108 .

FIG. 2B depicts the target layout pattern 303 and OPC enhancements, such as the corrected layout pattern 301 , of the connection lines. In some embodiments, the OPC enhanced layout pattern 301 of FIG. 2B is formed on a reticle, and the reticle is projected onto a wafer, such as wafer 108 , by the reticle projection system 106 of FIG. 1 .

Figure 3 depicts an example layout profile with two defect regions. FIG. 3 illustrates a photoresist pattern 300 with two defect regions 302 and 304 . When the corrected reticle layout M′ is projected onto the photoresist layer of wafer 108 after OPC processing, photoresist pattern 300 may be generated by reticle projector 130 as disclosed herein. As shown, the two defect regions 302 , 304 respectively include a bridge 312 and a bridge 314 (eg, short circuit), which are connections between adjacent layout lines in the middle of the defect regions 302 and 304 . In some embodiments, defect regions 302 and 304 are back-projected to two corresponding hot spot regions in corrected reticle layout M'. In some embodiments, ILT operations are performed on the corrected reticle layout M′, e.g., on hotspot regions in the corrected reticle layout M′, to correct light generated in the photoresist layer of wafer 108 The corresponding defect regions 302 and 304 of the resist pattern.

FIG. 4 depicts a schematic diagram of an example layout corrector. Figure 4 is configured to perform ILT enhancement. FIG. 4 shows the reticle booster 104 which receives the target layout pattern M at the input of the ILT booster 452 and produces an enhanced reticle layout 462 at the output of step 460 . In some embodiments, the ILT enhancer 452 receives the corrected reticle layout M' after the OPC operation. When the corrected reticle layout M' or target layout pattern M is projected onto the photoresist layer of wafer 108, the corrected reticle layout M' or target layout pattern M includes hot spots corresponding to defects on the photoresist layer area.

The ILT enhancer 452 performs enhancement, such as a constrained inverse filtering operation, on the corrected reticle layout M′ or the hot spot region of the target layout pattern M, and generates an iterative result, the enhanced reticle layout 462 . The enhanced mask layout 462 is projected onto the photoresist layer of the wafer 108 by the mask projector 130 to produce the projected photoresist pattern 458 . In some embodiments, reticle projector 130 performs analog projection and is consistent with operations performed by the configuration of FIG. 7A . The projected photoresist pattern 458 is inspected for defective areas by an ILT verifier 456 . The verification result 468 is tested at step 460 , and if the verification result 468 is not successful, eg, there is a defective area, the iteration continues by modifying the layout enhancement of the ILT enhancer 452 . The iteration continues until the verification result 468 is successful and the projected photoresist pattern 458 is free of any defect areas. When the verification result 468 is successful, an enhanced reticle layout 462 is provided at step 460 .

As shown, in addition to the reticle intensifier 104 , FIG. 4 also includes a reticle generator 141 and an optical system 145 . As described above, mask generator 141 generates mask 143 from enhanced mask layout 462 and optical system 145 of the photolithography system projects onto mask 143 and produces a photoresist pattern on the photoresist layer of wafer 108 . The reticle projector 130 is described in more detail with respect to Figures 7A and 7B.

5 depicts a schematic diagram of an example source sampler system 500 for optimizing a transmission cross coefficient (TCC) operator. FIG. 5 shows an input source 402 , such as an illumination source, and a TCC generator module 421 . In some embodiments, input source 402, such as an illumination source, is a parametric illumination source of an optical system of a lithography system (eg, optical systems 800 and 850 of FIGS. 8A and 8B ). In some embodiments, input source 402 is a laser source. In some embodiments, the input source 402 has a Gaussian profile with a standard deviation between about 1 cm and about 20 cm. In some embodiments, the input source 402 has a circular profile with a radius between 1 cm and 20 cm and a uniform amplitude. In some embodiments, input source 402 is one of a coherent or partially coherent source. In some embodiments, input source 402 is a non-coherent source. In some embodiments, the input source 402 is a deep ultraviolet (DUV) source having a wavelength of about 250 nm to about 100 nm, or an extreme ultraviolet (EUV) source having a wavelength of about 100 nm to about 10 nm. In some embodiments, the input source 402 has dimensions from about 1 cm by 1 cm (about 2 cm in diameter) to about 20 cm by 20 cm (about 40 cm in diameter). FIG. 5 also shows the discretized source operator 406 and the TCC generator module 423 . The discretized source operator 406 samples the input source 402 and provides a discretized source 420 . As shown in FIG. 5 , TCC generator module 421 uses input source 402 and optical parameters 411 including an exit pupil consistent with exit pupil 830 or 831 of FIGS. 8A and 8B and generates, e.g., computes, TCC operator 404 . TCC generator module 423 uses discrete source 420 and optical parameters 411 and generates (eg, computes) TCC operator 408 . In some embodiments, TCC generator modules 421 and 423 generate TCC operators 404 and 408 using equation (2) below. Also, as shown in FIG. 5 , source sampler system 500 provides TCC operators 404 and 408 and discrete source 420 as outputs.

Thus, in some embodiments, the TCC operator 404 depends on the input source 402 , such as the shape and size of the input source 402 , and the TCC operator 408 depends on the discrete source 420 , such as the distribution of sampling points of the input source 402 . As shown in equation (2) below, the TCC operator depends on the spatial Fourier transform of the input source. In addition, the TCC operators 404 and 408 depend on the optical parameters 411 of the lithography system, eg, the optical parameters 411 of the optical system of the lithography system. Thus, TCC operators 404 and 408 may depend on the wavelength of the illumination source of the optical system, the coherence amount of the illumination source, the numerical aperture of the optical system, the shape and size of the exit pupil of the optical system, and the aberrations of the optical system. In some embodiments, error calculator 410 determines an error between TCC operator 404 and TCC operator 408 . In some embodiments, error calculator 410 generates error 422 which is the sum of squared differences between TCC operator 404 and TCC operator 408, e.g., L2 norm, Frobenius norm, is The sum of the squared differences between the corresponding points of the TCC operator 404 and the TCC operator 408 .

In some embodiments, the intensity I of a projected image, such as the projected photoresist pattern 101 of FIG. 2A or the projected photoresist pattern 458 of FIG. 4 is defined by the following equations (1) and (2): I(x)= ∬ M(α)T(α,α') M ^* (α')e ^{2πi(α-α' )x} dadα'Equation (1) T(α,α')=∫S(α _s )P(α+ α _s )P ^* (α'+α _s )dα _s Equation (2) where α is the spatial frequency coordinate, M is the spatial Fourier transform of the layout pattern of the reticle, P is the exit pupil function of the optical system, and S is the illumination The spatial Fourier transform of the intensity distribution of the source, T is the TCC operator. In some embodiments, the TCC operator includes a spatial Fourier transform of the exit pupil function P and the illumination source S, as shown in equation (2). In addition, the TCC operator incorporates the integral operation of equation (1). In some embodiments, the exit pupil of the optical system is a virtual aperture such that only light rays passing through the exit pupil can exit the optical system. In some embodiments, the exit pupil function P(α) is the representation of the exit pupil as a function of the variable α, where α is a two-dimensional (2D) variable in a 2D coordinate system, such as a 2D point (α = (F _x and F _y )) in the frequency plane. In some embodiments, TCC generator modules 421 and 423 act as functions of two variables α and α' according to equation (2), and use TCC operator 404 and TCC operator 408 respectively to the intensity of equation (1). The function of I is evaluated numerically, generating TCC operator 404 and TCC operator 408 . Two variables α and α′ are sampled, and the intensity I of the TCC operator 404, TCC operator 408 and equation (1) is calculated at the sampling points of the variables. In some embodiments, the sampling resolution of the two variables α and α′ in the spatial frequency coordinates is higher than the corresponding sampling resolution of the input source 402, and thus in the calculation of equation (1), for the variables α and α′ The error caused by sampling to evaluate the intensity I of TCC operators 404 and 408 and equation (1) is negligible, eg, less than one percent. In some embodiments, the exit pupil function is a real function represented by an amplitude that is 1 inside the circle and 0 outside the circle. As shown above, the TCC operator depends on the exit pupil function and the illumination source distribution. In some embodiments, the exit pupil function is a complex function represented by the amplitude and phase at each point of the exit pupil function, wherein the phase of the pupil function includes aberrations of the optical system. The exit pupil is described with respect to Figures 8A and 8B. In some embodiments, the TCC operator is symmetric and positive definite, and thus can be expanded into separable cores φ _n and φ _n ^* with a non-negative expansion coefficient λ _n , as shown in equation (3) below: T(α, α')=∑ _n λ _n φ _n (α)φ _n *(α') , 𝝀 _𝒏 ≥𝟎, 𝒏=𝟏, 𝟐, 𝟑,… Equation (3)

In some embodiments, the kernel is evaluated numerically at sampling points of the variables α and α′. Additionally, in some embodiments, TCC operator 404 and TCC operator 408 are approximated as a weighted sum of a finite number of cores. In some embodiments, TCC operator 404 or TCC operator 408 is discretized and represented by a matrix, such as a 2D positive definite TCC matrix. In some embodiments, TCC operator 404 and TCC operator 408 are expanded over the same range of variables α and α′, thus, the TCC matrices corresponding to TCC operator 404 and TCC operator 408 have the same dimensions. Additionally, the integral of Equation (1) is expressed as a matrix multiplication of the TCC matrix and a discrete-space Fourier transform of the layout pattern M of the reticle. In some embodiments, the TCC generator modules 421 and 423 of the source sampler system 500 further perform discretization and provide the TCC operators 404 and 408 as TCC matrices at output. In addition, error calculator 410 generates error 422 as the sum of squared differences between corresponding elements of the TCC matrix.

Additionally, the kernels _φn and ^φn* _are discretized, respectively, and represented as horizontal or vertical vectors, eg, one-dimensional (1D) horizontal or 1D vertical matrices. In some embodiments, error calculator 410 generates error 422 as a sum of squared differences between corresponding elements of the TCC matrix. In some embodiments, when the TCC matrix is positive, the coefficient λ _{n is} used as a weight, and the TCC matrix is expanded into a weighted sum of multiple matrices, wherein each matrix is generated as each vertical vector sum with the core φ _n and φ _n ^* One of the products associated with the corresponding horizontal vectors. The weighted sum is the matrix form of equation (3). In some embodiments, TCC operator 404 or TCC operator 408 is expanded as a weighted sum of cores, as shown in equation (3). In some embodiments, TCC operator 404 and/or TCC operator 408 are approximated by selecting a subset of cores φ _n and φ _n ^* . Additionally, the projected image of the lithography mask is approximated by the approximated TCC operators 404 and 408 . In some embodiments, the limited number of cores is selected by sorting the non-negative coefficients λ _n and then selecting coefficients λ _n greater than a threshold and the cores associated with coefficients greater than the threshold. Coefficients λ _{n smaller than the threshold and kernels associated with coefficients λ n smaller} than the threshold are discarded.

After the error 422 is calculated by the error calculator 410 , the error is compared to a lower (first) threshold and an upper (second) threshold in operation 412 . If the error 422 is within the upper and lower thresholds, then the discrete source 420 is acceptable and the discrete source 420 is provided as an output. In some embodiments, the discrete source 420 and corresponding TCC operator 408 are used to compute the projection of the reticle in the reticle projector 130 of FIGS. 2A and 4 . In some embodiments, a singular value decomposition is used to define the cores and select the core with the highest energy. In some embodiments, determining the TCC operator 404 or the TCC operator 408 includes determining a cross-section between two exit pupils P having different offsets α and α′ as shown in equation (2). In some embodiments, when the illumination source is partially coherent, determining the TCC operator 404 or the TCC operator 408 includes determining a cross-section between the two exit pupils and a circle with a radius equal to the coherence length of the illumination source, thereby limiting Spatial Fourier transform S of the illumination source.

In some embodiments, if the error 422 is greater than a second threshold, the number of sampling points is increased (eg, based on the error 422 ) and the discrete source 420 is resampled. The re-sampling is performed by the re-discretization source 414 operator, and the TCC operator 408 is re-determined from the re-sampled discretization source. In some embodiments, by increasing the number of sampling points, error 422 is reduced. In some embodiments, if the error 422 is less than a first threshold, the number of sampling points is reduced (e.g., according to the error 422), the discretized source 420 is resampled by the re-discretized source 414 operator, and re-determined based on the re-sampled discretized source TCC operator 408 . In some embodiments, by reducing the number of sampling points, the computation time of the reticle projector 130 is reduced and computation of the projected image becomes faster. After reducing or increasing the number of sampling points, the error 422 is recalculated by the error calculator 410 to determine whether the error 422 remains between the first threshold and the second threshold. In some embodiments, the error 422 is bounded by other norms such as the L-infinity norm (maximum) or a linear algebraic norm (e.g., a Phoebenes norm or a nuclear norm), where the linear algebraic norm is expressed in terms of in the TCC matrix.

6A, 6B, and 6C depict schematic diagrams of example systems for sampling and resampling illumination sources and generating TCC operators. FIG. 6A shows a diagram for sampling an input source 402 . In some embodiments, input source 402 is a parametric illumination source as described above. The input source 402 is sampled by the sampler 630, which determines the number of sampling points and the distribution of the sampling points. In some embodiments, the sampler 630 uses the optical parameters 411 as described above to determine the number of sampling points of the input source 402 , such as the sampling resolution, to generate the discrete source 420 . In some embodiments, the sampler 630 uses a Nyquist rate to determine the number of sampling points according to the spatial frequency content of the input source 402 . In addition, the discrete source generator 632 receives the number of sampling points and determines how (eg, evenly or unevenly) the sampling points are distributed in the input source 402 . In some embodiments, the combination of the sampler 630 and the discrete source generator 632 is identical to the discretized source operator 406 of FIG. 5 .

FIG. 6B shows a graph for resampling a discrete source 420 . Discrete source 420 is resampled by resampler 624, which determines a modified number of sample points 634 and a distribution of the modified sample points. In some embodiments, resampler 624 uses optical parameters 411 and errors 422 as described above to determine a modified number of sampling points 634 of discrete source 420, eg, a modified sampling resolution, to produce a modified discrete source. In some embodiments, the discrete source generator 626 receives the modified number of sampling points 634 and determines how the modified sampling points are distributed. In some embodiments, the combination of resampler 624 and discretization source generator 626 is consistent with rediscretization source 414 of FIG. 5 . In some embodiments, local or global operators are used for resampling. In some embodiments, a discrete Fourier transform operator is used for resampling such that the original sample points of the discrete source 420 are Fourier transformed into the frequency domain. Then, the inverse Fourier transform is applied to the frequency domain to generate a continuous inverse Fourier transform function in the spatial domain. The inverse Fourier transform function is sampled at locations defined by the discrete source generator 626 by a modified number of sample points.

FIG. 6C shows a graph for distributing and defining a location of a modified number of sampling points. The intensity position initializer 642 receives the modified number of sample points and evenly distributes the modified number of sample points. The discretization source operator 406 finds the intensity of a modified number of sample points, for example by performing the Fourier Transform/Inverse Fourier Transform described above. The discretized source operator 406 generates a new discretized source 420 . At operation 621 , an error 422 is calculated between the TCC operator 408 and the TCC operator 404 when the new TCC operator 408 is generated using the new discrete source 420 . Intensity position adjuster 625 recursively modifies the position of the modified number of sample points until error 422 is minimized. When the error 422 is minimized, a new discrete source 420 is generated. In some embodiments, error 422 is minimized when error 422 is between a second threshold defined with respect to FIG. 5 .

7A and 7B illustrate schematic diagrams of example systems for computing projected images using TCC operators. FIGS. 7A and 7B illustrate different embodiments of the reticle projector 130 of FIGS. 2A and 4 consistent with the reticle projector 130 of FIG. 5 . FIG. 7A shows a projected image calculator 702 that, consistent with equation (1), generates the result of executing the TCC operator 404 on the layout pattern of the reticle 143 to produce the projected resist pattern 101 of FIG. 2A or FIG. 4 Projected image 706 consistent with projected photoresist pattern 458 of . FIG. 7B shows a projected image calculator 702 that, consistent with equation (1), generates the result of executing the TCC operator 408 on the layout pattern of the reticle 143 to produce the projected resist pattern 101 of FIG. 2A or FIG. 4 Projected image 708 consistent with projected photoresist pattern 458. As shown in FIG. 7B , in some embodiments, the TCC operator may be broken down into cores by core signal generator 704 and cores 710 are used by projected image calculator 703 to generate projected image 708 .

8A and 8B depict a schematic view of an example optical system of an optical system of a lithography system. Figure 8A illustrates an optical system 800 used in a lithography system in some embodiments. Optical system 800 shows illumination source 802 at distance 808 from lens 804 . The mirror 804 transmits the radiation beam of the light source through the mask 143 . Transmitted radiation beam 810 is converged using objective lens system 806 to generate convergent beam 812 and make a projected image of reticle 143 on wafer 108 . As shown, the blades 814 block any radiation outside the exit pupil 830 of the optical system 800 . Figure 8B shows an optical system 850 used in a lithography system in some embodiments. Optical system 850 shows illumination source 802 . Mirror 804 transmits the radiation beam of illumination source 802 . The radiation beam is reflected by the mirror 820 and directed towards a reticle 843 , eg a reflective reticle, and produces a reflected radiation beam 811 that reflects from the reticle 843 . Reflected radiation beam 811 is converged using objective lens system 806 to generate convergent beam 812 and produce a projected image of reflective reticle 843 on wafer 108 . FIG. 8B also shows exit pupil 831 of optical system 850 .

9 depicts a flowchart of an example process for enhancing a reticle according to some embodiments of the present disclosure. Process 900 may be performed by the systems of FIGS. 2A and 11 . In some embodiments, process 900 or a portion of process 900 is performed and/or controlled by computer system 1000 described below with reference to FIGS. 10A and 10B . In some embodiments, process 900 is performed by system 1100 of FIG. 11 . The method includes operation S902 of determining a first TCC operator of an optical system of the lithography system according to an illumination source of the optical system. In some embodiments, the TCC operator 404 of FIG. 7A is generated from an input source 402 (eg, an illumination source). In operation S904 , an illumination source of the optical system, such as the input source 402 , is sampled by a first number of sampling points to generate a discrete source 420 . In operation S906, a second TCC operator of the optical system of the lithography system is determined according to the discrete source. In some embodiments, the TCC operator 408 of FIG. 7B is determined from a discrete source 420 .

In operation S908, an error between the first TCC operator and the second TCC operator is determined. In some embodiments, the first TCC operator and the second TCC operator are discretized respectively, and the first TCC matrix and the second TCC matrix are generated. An error is determined between the first TCC matrix and the second TCC matrix. In operation S910, the first number of sampling points are recursively adjusted until the error is below a threshold level, and a final discrete source and a final second TCC operator 408 are determined. In some embodiments, the first number of sampling points are adjusted as described with respect to FIG. 11 . In some embodiments, iterations continue until the error is less than or equal to a threshold. In some embodiments, the error is positive, and the first number of sample points are modified to keep the error within the error range such that the error is less than a positive second threshold level, but greater than a positive first threshold level, less than a second threshold level. In some embodiments, if the error is greater than a second threshold level, the first number of sampling points is increased to increase the accuracy of determining, eg, computing the projected image of reticle projector 130 of FIGS. 2A , 4, 7A and 7B. Conversely, if the error is less than the first threshold level, the first number of sampling points are reduced to increase the speed of determining (eg, calculating) the projected image of the reticle projector 130 of FIGS. 2A , 4, 7A and 7B.

10A and 10B illustrate an apparatus for enhancing a reticle according to some embodiments of the present disclosure. In some embodiments, computer system 1000 is used to enhance a reticle. Thus, in some embodiments, computer system 1000 performs the functions of OPC enhancer 122, reticle projector 130, and OPC verifier 140 of FIG. 2A. In some embodiments, computer system 1000 performs the functions of analyzer module 1130 , master controller 1140 , reticle intensifier 1104 , and reticle validator 1108 , as will be described in FIG. 11 . In some embodiments, computer system 1000 performs simulations of reticle projector 1106 and optical system 1105 . 10A is a schematic diagram of a computer system performing reticle enhancement. All or part of the processing procedures, methods and/or operations of the foregoing embodiments can be realized by using computer hardware and computer programs executed thereon. In FIG. 10A , a computer system 1000 has a computer 1001 including a read-only memory (eg, CD-ROM or DVD-ROM) drive 1005 and a disk drive 1006 , a keyboard 1002 , a mouse 1003 , and a display 1004 .

FIG. 10B is a diagram showing the internal configuration of the computer system 1000 . In Fig. 10B, in addition to the optical disk drive 1005 and the magnetic disk drive 1006, the computer 1001 also has one or more processors, such as a microprocessor (MPU) 1011, a read-only memory (ROM) 1012 which stores programs such as startup program, random access memory (RAM) 1013 connected to MPU1011, which temporarily stores the instructions of the application program and provides a temporary storage area, hard disk 1014, which stores application programs, system programs and data, and bus 1015, which connects to the MPU1011 , ROM 1012 and so on. Note that computer 1001 may include a network card (not shown here) for providing a connection to a LAN.

In the aforementioned embodiments, the functions for causing the computer system 1000 to execute the device for enhancing the mask may be stored in the optical disc 1021 or the magnetic disc 1022, inserted into the optical disc drive 1005 or the magnetic disc drive 1006, and transmitted to hard drive 1014. Alternatively, the programs may be transferred to the computer 1001 via a network (not shown) and stored in the hard disk 1014 . At execution time, the program is loaded into RAM 1013 . Programs can be loaded from CD 1021 or floppy disk 1022 or directly from the Internet. The program does not necessarily include, for example, an operating system (OS) or a third-party program, so that the computer 1001 executes the function for enhancing the mask in the foregoing embodiments. The program may consist only of instructions to call the appropriate functions (modules) in a controlled mode and achieve the desired result.

FIG. 11 depicts an example system 1100 for enhancing a reticle according to some embodiments of the present disclosure. The system 1100 includes an analyzer module 1130 and a main controller 1140 coupled to each other. The analyzer module 1130 receives the layout pattern 1110 consistent with the target layout pattern M of FIGS. 1 and 2A . Analyzer module 1130 may send layout pattern 1110 to reticle booster 1104 coupled to master controller 1140 . In some embodiments, an analyzer module 1130 consistent with the discretization source operator 406 and the re-discretization source 414 of FIG. 5 determines an initial number of sampling points and an initial location of the sampling points. The initial locations of the sampling points may be uniformly distributed in the intensity or amplitude profile distribution of the illumination source 1107, which is consistent with the illumination source 802 of FIGS. 8A and 8B. Master controller 1140 is also coupled to reticle projector 1106, optical system 1105, and reticle inspector 1108 that are consistent with reticle projector 130 of FIGS. 1 and 2A. Optical system 1105 is identical to optical systems 800 and 850 of FIGS. 8A and 8B , and reticle inspector 1108 is identical to OPC inspector 140 of FIG. 2A and ILT inspector 456 of FIG. 4 .

In some embodiments, reticle booster 1104 performs OPC or ILT operations on layout pattern 1110 , and reticle booster 1104 is identical to ILT booster 452 of FIG. 4 or OPC booster 122 of FIG. 2A . In some embodiments, instead of the reticle booster 1104, the analyzer module 1130 performs OPC or ILT operations on the layout pattern 1110, thus, the analyzer module 1130 further cooperates with the ILT booster 452 of FIG. 4 or the OPC booster of FIG. 2A Device 122 is consistent. In some embodiments, reticle intensifier 1104 or analyzer module 1130 determines a TCC operator, such as TCC operator 404 or TCC operator 408, of optical system 1105 of a lithography system, and, accordingly, reticle intensifier 1104 Or analyzer module 1130 and master controller 1140 together further correspond to source sampler system 500 . In some embodiments, optical system 1105 is identical to optical systems 800 and 850 of FIGS. 8A and 8B . In some embodiments, the reticle intensifier 1104 or the analyzer module 1130 determines the TCC operator of the optical system 1105 of the lithography system based on an illumination source, such as the illumination source 802 of FIG. 8A or 8B or the illumination source 1107 of FIG. 11 , such as the TCC operator 404 . Additionally, the reticle intensifier 1104 or the analyzer module 1130 determines the optical lithography system's optical output pupils based on the optical system's exit pupils, eg, exit pupils 830 and 831 of FIGS. 8A and 8B as shown in Equation (2). TCC operator for system 1105 . Reticle booster 1104 or analyzer module 1130 also determines other TCC operators for optical system 1105 or optical systems 800 and 850 of FIGS. , such as the TCC operator 408 .

As shown in system 1100 , reticle booster 1104 is coupled to analyzer module 1130 through master controller 1140 . In some embodiments, reticle intensifier 1104 is identical to OPC intensifier 122 of FIG. 2A . System 1100 includes reticle projector 1106 coupled to analyzer module 1130 through master controller 1140 . In some embodiments, reticle projector 1106 is identical to reticle projector 130 of FIG. 2A . System 1100 also includes reticle validator 1108 coupled to analyzer module 1130 through master controller 1140 . In some embodiments, reticle projector 1106 is identical to reticle projector 130 of FIG. 2A . System 1100 also includes reticle validator 1108 coupled to analyzer module 1130 through master controller 1140 . In some embodiments, reticle validator 1108 is identical to OPC validator 140 of FIG. 2A as noted. In some embodiments, reticle intensifier 1104 , reticle projector 1106 and reticle inspector 1108 are included in master controller 1140 . In some embodiments, the adjustment to the first number of sampling points is performed by either the analyzer module 1130 or the reticle intensifier 1104 . In some embodiments, the reticle projector 1106 is consistent with a combination of the operations performed in FIGS. 7A and 7B .

In some embodiments, the illumination source, such as input source 402 of FIGS. 5 and 6A , is a polarized illumination source. Accordingly, each of the electric field or magnetic field at each point of the input source 402 can be represented by a vector in a plane perpendicular to the direction of travel of the light. In some embodiments, the light at each point of the input source 402 travels in the Z direction, therefore, the electric or magnetic field of the light is in the XY plane and can be represented by components in the X and Y directions. In some embodiments, at each spatial frequency α _s , the spatial Fourier transform S of the intensity distribution of the input source 402 is expressed as a 2 by 2 matrix S _{2 × 2} in equation (4) below, where S _xy = S ^* _yx .

In some embodiments, the polarization of the input source 402 varies continuously over time, and, therefore, instead of the temporal value of the input source 402, an electric field in both the X direction (s _xx ) and the Y direction (s _yy ) or The time-averaged variance of the magnetic field and the time-averaged covariance of the electric or magnetic field in two directions (s _xy or s _yx ). In some embodiments, the matrix elements of equation (4) are the spatial Fourier transforms of the variance and covariance functions at the spatial frequency α _s .

12 shows a schematic diagram of an example source sampler system for a TCC operator optimized for vector optics. FIG. 12 shows a vector source, such as a polarized illumination source 1202 . The variance and covariance of the polarized illumination sources 1202 are determined (eg, calculated) as described above. As shown, the first source component 1204 is the variance s _xx of the polarized illumination source 1202 , the second source component 1206 is the variance s _yy of the polarized illumination source 1202 , and the third source component 1208 is the covariance of the polarized illumination source 1202 . Variance s _xy . Due to the symmetry of the covariance, one of s _xy or s _yx is used. The first, second and third source components 1204, 1206 and 1208 serve as independent illumination sources for the three source sampler system 500 of FIG. As shown in FIG. 5, each source sampler system 500 provides a sampled/resampled discrete source 420 at the output. At operation 430 , the sampled/resampled discrete source 420 is component-wise added and the polarized sampled/resampled illumination source 1210 is generated. In some embodiments, polarized illumination source 1202 has not been sampled, and each source sampler system 500 provides a sampled source. In some embodiments, polarized illumination sources 1202 have already been sampled, and each source sampler system 500 provides a re- sampled source. In some embodiments, a single sampling resolution is selected for the first, second and third source components 1204 , 1206 and 1208 . In some embodiments, the highest sampling resolution provided by the three source sampler systems 500 is selected for all three source sampler systems 500 . The source components having a lower sampling resolution than the highest sampling resolution are resampled such that the first, second and third source components 1204, 1206 and 1208 have the same highest sampling resolution. The first, second and third source components 1204 , 1206 and 1208 are combined to produce a single polarized sampled illumination source 1210 . Then, using the components of the single polarized sampling illumination source 1210, the TCC operator or TCC matrix corresponding to the single polarized sampling illumination source 1210 is calculated using a generalization of equation (2) to determine the TCC operator or TCC matrix, and The intensity I of the projected image is determined by generalization of equation (1) using the TCC operator or TCC matrix.

According to some embodiments of the present disclosure, a method of enhancing a layout pattern includes determining a first transmission cross coefficient (TCC) operator of an optical system of a lithography system according to an illumination source of the optical system of the lithography system. The method includes sampling an illumination source of the optical system by a first number of sampling points to generate a first discrete source, and determining a second TCC operator of the optical system of the lithography system based on the first discrete source. The method further includes determining an error between the first TCC operator and the second TCC operator. The method further includes recursively adjusting the first number of sampling points to resample the illumination source and redetermining the second TCC operator based on the resampled illumination source until the error is below a threshold level and determining a final discrete source and a final second TCC operator. The method includes performing an optical proximity correction (OPC) operation of the first layout pattern of the reticle, the OPC operation using a final discrete source and a final second TCC operator to determine a projected projection of the first layout pattern of the reticle on the wafer. image. In one embodiment, the first layout pattern of the reticle includes one or more specific features, and the photoresist of the projected image of the first layout pattern on the wafer is determined using a final discrete source and a final second TCC operator. Generate one or more specific features on a layer. In one embodiment, the specific features include one or more of curvature, vertical lines or horizontal lines. In an embodiment, the method further comprises receiving an illumination profile of the illumination source and sampling the illumination profile of the illumination source at positions equal to the first number of sampling points. In an embodiment, sampling the illumination source is non-uniform sampling and resampling the illumination source is uniform sampling. In one embodiment, the illumination profile is one of an amplitude profile or an intensity profile of the illumination source. In one embodiment, the method further includes generating the OPC corrected first layout pattern on the reticle substrate to fabricate the reticle.

According to some embodiments of the present disclosure, a method for enhancing a layout pattern includes determining a first transmission cross coefficient ( TCC) operator, the method includes sampling the illumination source of the optical system through a first number of sampling points at a first number of sampling positions to form a first discrete source, and according to the first discrete source and the exit pupil of the optical system A second TCC operator of an optical system of the lithography system is determined. The method further includes determining an error between the first TCC operator and the second TCC operator. The method further includes recursively adjusting the first number of sample points and the first number of sample positions to resample the illumination source and re-determining the second TCC operator based on the resampled illumination source until the error is within a threshold error and eventually discrete The source and final second TCC operators are determined with a threshold error range having upper and lower bounds. The method includes performing an inverse lithography transformation (ILT) operation on a first layout pattern of the reticle, the ILT operation using a final discrete source and a final second TCC operator to determine a projected projection of the first layout pattern of the reticle on the wafer. The image is used to determine the ILT-enhanced first layout pattern and generate the ILT-enhanced first layout pattern on the reticle substrate to fabricate the reticle. In one embodiment, the error is above the upper limit of the threshold error range and resampling the illumination source includes increasing the first number of sampling points to a second number of sampling points, using the second number of sampling points to homogenize the illumination source sampling, recursively adjust the sampling position of the second number of sampling points to re-sample the illumination source, and re-determine the second TCC operator according to the re-sampled illumination source until the error is minimized. In one embodiment, the error is below the lower limit of the threshold error range and resampling the illumination source includes reducing the first number of sampling points to a second number of sampling points, using the second number of sampling points to homogenize the illumination source sampling, recursively adjust the sampling position of the second number of sampling points to re-sample the illumination source, and re-determine the second TCC operator according to the re-sampled illumination source until the error is minimized. In an embodiment, the method further comprises representing the final second TCC operator by a weighted sum of a plurality of cores in the core space, approximating the final second TCC operator by a weighted sum of two or more of the plurality of cores two TCC operators, and using the approximated final second TCC operator and the first discrete source to determine a projected image of the first layout pattern of the reticle on the wafer. In one embodiment, the first TCC operator and the second TCC operator are discretized to generate the first TCC matrix and the second TCC matrix, respectively, and the method further includes determining the difference between the first TCC matrix and the second TCC matrix The error is determined by the Forbinis norm error between . In one embodiment, the method further includes before performing the ILT operation on the first layout pattern: performing an optical proximity correction (OPC) operation on the first layout pattern, the ILT operation using the final discrete source and the final second TCC operator to determine A projected image of the first layout pattern of the reticle on the wafer, and performing an ILT operation of the OPC corrected first layout pattern using the final discrete source and the final second TCC operator to determine the OPC corrected first layout pattern of the reticle on the wafer A projected image of a layout pattern. In an embodiment, the method further includes receiving a second layout pattern of a reticle of the lithography system different from the first layout pattern, and performing an ILT of the second layout pattern using the final discrete source and the final second TCC operator to A projected image of the second layout pattern of the reticle on the wafer is determined.

According to some embodiments of the present disclosure, a lithography system includes a main controller, a reticle, a reticle intensifier coupled to the main controller, an optical system including an illumination source and coupled to the main controller, and a light source coupled to the main controller and the light source. The reticle projector of the mask intensifier, and produces projections on the reticle on the wafer. The system further includes an analyzer module coupled to the main controller, the analyzer module receives the reticle to produce the first layout pattern on the wafer, the reticle booster is coupled to the analyzer module through the main controller, and One of an optical proximity correction (OPC) operation or an inverse lithography transformation (ILT) operation of the first layout pattern is performed. The reticle booster also determines a final discrete source and a final second TCC operator by receiving a first number of sampling points from the analyzer module, determining the lithography system based on the illumination source of the optical system and the exit pupil of the optical system The first transmission cross coefficient (TCC) operator of the optical system, samples the illumination source of the optical system through the first number of sampling points to form the first discrete source, determined according to the first discrete source and the exit pupil of the optical system A second TCC operator of the optical system of the lithography system, determining an error between the first TCC operator and the second TCC operator, and recursively adjusting the first number of sampling points to resample the illumination source and based on the resampled The illumination source re-determines the second TCC operator until the error is below a threshold level and determines the final discrete source and the final second TCC operator. The reticle projector performs projection onto the reticle on the wafer using a final discrete source and a final second TCC operator for an OPC operation or an ILT operation to determine a projected first layout pattern of the reticle on the wafer image. In one embodiment, the illumination source is a laser source. In one embodiment, the illumination source is one of a coherent source or a partially coherent source. In one embodiment, the profile of the illumination source is a circular profile with a radius between 1 cm and 20 cm and a constant amplitude, or a Gaussian profile with a standard deviation between 1 cm and 20 cm. In an embodiment, the illumination source of the optical system is a polarized illumination source having two time-varying electrical or magnetic components in a first direction and a second direction perpendicular to the first direction. The first direction and the second direction are perpendicular to the direction of travel of the light beam of the polarized illumination source. The analyzer module further determines a first variance profile of the components in the first direction, a second variance profile of the components in the second direction, and a covariance between the components of the first and second directions for the polarized illumination source contour. The reticle enhancer also assigns one of the first variance profile, the second variance profile, or the covariance profile to the profile of the illumination source, determining a final result of the assigned first variance profile, second variance profile, or covariance profile The profiles are discretized and a final second TCC operator of the assigned first variance profile, second variance profile or covariance profile is determined. The reticle projector also uses the determined final discrete profile and the final second TCC operator to perform mapping of the first layout pattern of the reticle with an assigned profile of polarized illumination sources on the wafer for OPC operation or ILT operation. projection. In one embodiment, the illumination source is one of deep ultraviolet or extreme ultraviolet illumination.

In some embodiments, the processes and methods described above are implemented to adapt the target layout pattern to the modified target layout pattern by using projection simulations. The illumination source of the simulated projection is the illumination source of the optical system of the sampled lithography system. The number of sampling points is adjusted so that the number of sampling points is not too large to cause a computational burden, and the number of sampling points is not too small to cause a difference between the simulated projection and the real projection. Therefore, the method described above provides an effective number of sampling points to keep the error between simulated and real projections within a desired range without causing unnecessary calculations.

The features of several embodiments have been summarized above so that those skilled in the art can better understand aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure to design or modify other programs and structures to achieve the same purpose and/or achieve the same advantages as the embodiments introduced herein a foundation. Those skilled in the art should also realize that such equivalent constructions should not depart from the spirit and scope of the present disclosure, and that they can make various changes, substitutions and changes herein without departing from the spirit and scope of the present disclosure.

100: Integrated circuit manufacturing process 101: Photoresist pattern 102:Integrated circuit design module 103: Verification signal 104: Reticle intensifier 106: Mask projection system 108: Wafer 122:Optical Proximity Correction (OPC) Enhancer 130: Mask projector 140: OPC validator 141: Mask generator 143: mask 145: Optical system 150: step 300: photoresist pattern 301: Layout pattern 302: defect area 303: Layout pattern 304: Defect area 312: bridge part 314: bridge part 402: input source 404: TCC operator 406: Discretization source 408: TCC operator 410: Error Calculator 411: Optical parameters 412: Step 414:Rediscretize source 420: Discrete Source 421: TCC generator module 422: error 423: TCC generator module 452: Inverse Lithography Transformation (ILT) Enhancer 456:ILT validator 458: Photoresist pattern 460: step 462: Mask layout 468: Verification result 500:Source sampler 621: Step 624:Resampler 625: Intensity Position Regulator 626: Discrete Source Generator 630: Sampler 632: Discrete Source Generator 634: Sampling point 642:Intensity position initializer 702: Projection Image Calculator 703: Projection Image Calculator 704: core signal generator 706: Projection image 708: Projection image 710: core 800: Optical system 802: Lighting source 804: Lens 806: Objective lens system 808: Distance 810: Radiation Beam 811: Reflecting Radiation Beams 812: Convergent Beam 814: blade 820: mirror surface 830: exit pupil 831: exit pupil 843: mask 850: Optical system 900: Handler S902: Step block S904: step block S906: Step block S908: Step block S910: Step block 1000: computer system 1001: computer 1002: keyboard 1003: mouse 1004: display 1005:CD player 1006:Disk drive 1011: Microprocessor 1012: ROM 1013: random access memory 1014: hard disk 1015: busbar 1021:CD 1022: Disk 1100: system 1104: Reticle Enhancer 1105: Optical system 1106: Mask projector 1107: lighting source 1108: Mask validator 1110: layout pattern 1130: Analyzer module 1140: Main controller 1202: vector source 1204: the first source component 1206: the second source component 1208: The third source component 1210: Sample/resample vector source M: target layout pattern M': Enhance or correct layout patterns

Aspects of the present disclosure are best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, in accordance with the standard practice in the industry, various components are not drawn to scale. In fact, the dimensions of the various components may be arbitrarily increased or decreased for clarity of discussion.

FIG. 1 depicts a schematic diagram of an example integrated circuit (IC) fabrication process.

2A and 2B depict schematic diagrams of example reticle boosters and OPC booster layout patterns associated with target layout patterns.

Figure 3 depicts an example layout profile with two defect regions.

FIG. 4 illustrates a schematic diagram of an example layout corrector.

5 depicts a schematic diagram of an example source sampler system for optimizing a transmission cross coefficient (TCC) operator.

6A, 6B, and 6C depict example system schematics for sampling and resampling illumination sources and generating TCC operators.

7A and 7B are schematic diagrams illustrating an exemplary system for computing projected images using TCC operators according to some embodiments of the present disclosure.

8A and 8B illustrate exemplary optical system diagrams of an optical system of a lithography system.

9 depicts an example process flow diagram for enhancing a reticle according to some embodiments of the present disclosure.

10A and 10B illustrate an apparatus for enhancing a reticle according to some embodiments of the present disclosure.

FIG. 11 depicts an example system for enhancing a reticle according to some embodiments of the present disclosure.

12 depicts a schematic diagram of an example source sampler system for a TCC operator optimized for vector optics.

100: Integrated circuit manufacturing process

102:Integrated circuit design module

104: Reticle intensifier

106: Mask projection system

108: Wafer

M: layout pattern

Claims (10)

A method of designing a layout comprising: determining a first transmission cross coefficient (TCC) operator of an optical system of a lithography system based on an illumination source of the optical system of the lithography system; sampling the illumination source of the optical system by a first number of sampling points to generate a first discrete source; determining a second TCC operator of the optical system of the lithography system based on the first discrete source; determining an error between the first TCC operator and the second TCC operator; recursively adjusting the first number of sampling points to resample the illumination source and re-determining the second TCC operator based on the resampled illumination source until the error is below a threshold level and a final discrete source and a final a second TCC operator is determined; and performing an optical proximity correction (OPC) operation of a first layout pattern of a reticle, wherein the OPC operation uses the final discrete source and the final second TCC operator to determine the first of the reticle on a wafer A projected image of a layout pattern. The method of claim 1, wherein the first layout pattern of the reticle includes one or more specific features, and wherein the final discrete source and the final second TCC operator are used to determine the economics of the first layout pattern The projected image creates one or more specific features on a photoresist layer of the wafer. The method of claim 1, further comprising: An illumination profile of the illumination source is received and the illumination profile of the illumination source is sampled at a number of locations, wherein the number is equal to the first number of sampling points. A method of designing a layout comprising: determining a first transmission cross coefficient (TCC) operator of an optical system of a lithography system based on an illumination source of an optical system of the lithography system and an exit pupil of the optical system of the lithography system; sampling the illumination source of the optical system at a first number of sampling locations through a first number of sampling points to form a first discrete source; determining a second TCC operator of the optical system of the lithography system based on the first discrete source and the exit pupil of the optical system; determining an error between the first TCC operator and the second TCC operator; recursively adjusting the first number of sampling points and the first number of sampling positions to resample the illumination source and re-determine the second TCC operator based on the resampled illumination source until the error is within a threshold error range and a final discrete source and a final second TCC operator are determined, wherein the threshold error range has an upper bound and a lower bound; performing an inverse lithography transformation (ILT) operation on a first layout pattern of a reticle, wherein the ILT operation uses the final discrete source and the final second TCC operator to determine the reticle on a wafer a projected image of the first layout pattern used to determine an ILT enhancement of the first layout pattern; and The ILT enhanced first layout pattern is generated on a reticle substrate to fabricate a reticle. The method of claim 4, wherein the error is above the upper limit of the threshold error range, and wherein resampling the illumination source comprises: increasing the first number of sampling points to a second number of sampling points; uniformly sample the illumination source with the second number of sampling points; and The sampling position of the second number of sampling points is adjusted recursively to re-sample the illumination source, and the second TCC operator is re-determined according to the re-sampled illumination source until the error is minimized. The method of claim 4, wherein the error is below the lower limit of the threshold error range, and wherein resampling the illumination source includes reducing the first number of sampling points to the second number of sampling points; uniformly sample the illumination source with the second number of sampling points; and The sampling positions of the second number of sampling points are recursively adjusted to re-sample the illumination source, and the second TCC operator is re-determined according to the re-sampled illumination source until the error is minimized. The method of claim 4, further comprising: representing the final second TCC operator by a weighted sum of cores in a core space; approximating the final second TCC operator by a weighted sum of two or more cores of the plurality of cores; and The projected image of the first layout pattern of the reticle on the wafer is determined using the approximate final second TCC operator and the first discrete source. A lithography system comprising: a master controller; a photomask; a reticle intensifier coupled to the master controller; an optical system including an illumination source coupled to the master controller; a reticle projector coupled to the main controller and the reticle intensifier and configured to produce a projection on the reticle on a wafer; and an analyzer module coupled to the main controller, wherein the analyzer module is configured to receive the reticle to produce a first layout pattern on the wafer, wherein the reticle booster is coupled to the analyzer module through the master controller, and wherein is configured to receive the first layout pattern from the analyzer module and perform an optical proximity correction of the first layout pattern ( OPC) operation or an Inverse Lithography Transformation (ILT) operation, and Wherein the reticle booster is further configured to determine a final discrete source and a final second TCC operator by: receiving a first number of sampling points from the analyzer module; determining a first transmission cross coefficient (TCC) operator of the optical system of the lithography system according to the illumination source of the optical system and an exit pupil of the optical system; sampling the illumination source of the optical system by the first number of sampling points to produce a first discrete source; determining a second TCC operator of the optical system of the lithography system based on the first discrete source and the exit pupil of the optical system; determining an error between the first TCC operator and the second TCC operator; recursively adjusting the first number of sampling points to resample the illumination source and redetermining the second TCC operator based on the resampled illumination source until the error is below a threshold level and a final discrete source and a final discrete source are determined the final second TCC operator; and wherein the reticle projector is configured to perform the projection of the reticle onto the wafer using the final discrete source and the final second TCC operator for the OPC operation or the ILT operation to determine the wafer A projected image of the first layout pattern of the reticle on a circle. The lithography system of claim 8, wherein the illumination source is a laser source. The lithography system according to claim 8, wherein the illumination source is one of a coherent source or a part of a coherent source.

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